1. Field of the Invention
This invention relates to tube couplings and in particular to tube couplings for use with tubes having a feature such as a flange, projection or groove with which positive engagement is to be made by the coupling. For example, the coupling may be used in the fuel or a brake line of a motor vehicle.
2. Background Prior Art
European Patent Publication No. 0 663 557 discloses a tube coupling comprising a coupling body having a throughway open at one end to receive a tube, an open ended housing on the body projecting from said one end thereof through which a tube may extend into the throughway and the body. A collet is mounted in the housing for limited axial movement and has an annular part with resilient legs projecting therefrom towards the open end of the housing and terminating in means to engage a formation on the tube to hold the tube in the coupling body. The housing has an end region remote from the coupling body in which the collet ends are constrained against expansion to release a tube hold thereby and an intermediate region in which the ends may expand to release a tube and means are provided on the collat projecting into and held in the throughway of the coupling body when a tube is present to restrain the collet so that the free ends of the collet legs are prevented from moving beyond the end region of the housing to a position in which they could expand and release the tube. This arrangement has the disadvantage that it is necessary to provide a means of restraint for limiting axial movement of the collet in the coupling body. This may be in the form of a second collet arrangement or an interlock arrangement with the coupling body. An object of the invention is to simplify the construction to avoid the need for such a secondary device.